Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), Spain; Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Spain.
Department of Neurology, Uniklinikum C. G. Carus, Dresden, Germany.
Biochim Biophys Acta Mol Basis Dis. 2020 Jun 1;1866(6):165726. doi: 10.1016/j.bbadis.2020.165726. Epub 2020 Feb 13.
Mitochondrial diseases are considered rare genetic disorders characterized by defects in oxidative phosphorylation (OXPHOS). They can be provoked by mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA). MERRF (Myoclonic Epilepsy with Ragged-Red Fibers) syndrome is one of the most frequent mitochondrial diseases, principally caused by the m.8344A>G mutation in mtDNA, which affects the translation of all mtDNA-encoded proteins and therefore impairs mitochondrial function. In the present work, we evaluated autophagy and mitophagy flux in transmitochondrial cybrids and fibroblasts derived from a MERRF patient, reporting that Parkin-mediated mitophagy is increased in MERRF cell cultures. Our results suggest that supplementation with coenzyme Q (CoQ), a component of the electron transport chain (ETC) and lipid antioxidant, prevents Parkin translocation to the mitochondria. In addition, CoQ acts as an enhancer of autophagy and mitophagy flux, which partially improves cell pathophysiology. The significance of Parkin-mediated mitophagy in cell survival was evaluated by silencing the expression of Parkin in MERRF cybrids. Our results show that mitophagy acts as a cell survival mechanism in mutant cells. To confirm these results in one of the main affected cell types in MERRF syndrome, mutant induced neurons (iNs) were generated by direct reprogramming of patients-derived skin fibroblasts. The treatment of MERRF iNs with Guttaquinon CoQ (GuttaQ), a water-soluble derivative of CoQ, revealed a significant improvement in cell bioenergetics. These results indicate that iNs, along with fibroblasts and cybrids, can be utilized as reliable cellular models to shed light on disease pathomechanisms as well as for drug screening.
线粒体疾病被认为是罕见的遗传疾病，其特征是氧化磷酸化（OXPHOS）缺陷。它们可以由核 DNA（nDNA）或线粒体 DNA（mtDNA）的突变引起。MERRF（肌阵挛性癫痫伴破碎红纤维）综合征是最常见的线粒体疾病之一，主要由 mtDNA 中的 m.8344A>G 突变引起，该突变影响所有 mtDNA 编码蛋白的翻译，从而损害线粒体功能。在本工作中，我们评估了源自 MERRF 患者的线粒体转移细胞和成纤维细胞中的自噬和 mitophagy 流，报告 Parkin 介导的 mitophagy 在 MERRF 细胞培养物中增加。我们的结果表明，补充辅酶 Q（CoQ），一种电子传递链（ETC）和脂质抗氧化剂的成分，可以防止 Parkin 易位到线粒体。此外，CoQ 作为自噬和 mitophagy 流的增强剂，部分改善了细胞病理生理学。通过沉默 MERRF 细胞中的 Parkin 表达来评估 Parkin 介导的 mitophagy 在细胞存活中的意义。我们的结果表明，mitophagy 作为突变细胞的存活机制发挥作用。为了在 MERRF 综合征的主要受影响细胞类型之一中证实这些结果，通过直接重编程患者来源的皮肤成纤维细胞生成了突变诱导神经元（iNs）。用 Guttaquinon CoQ（GuttaQ），一种 CoQ 的水溶性衍生物，处理 MERRF iNs 显示出细胞生物能量学的显著改善。这些结果表明，iNs 与成纤维细胞和线粒体转移细胞一样，可以用作可靠的细胞模型，以阐明疾病发病机制并进行药物筛选。
